Catherine Holmes
by Earwen Mitrandir
Summary: When John comes home from doing the groceries, a young woman is sitting in the corner of Sherlock and John's flat. Who is she and what is she up to? Pranking. Yes. I'm not pulling your leg. Please come in and R&R! Hope you'll enjoy! :) Rating: K for now and warning: Johnlock, but not dominant. Still writing but updates will be as frequent as possible. :) Chapter 2 is up!
1. Chapter 1

**SO! Hi again! New story! :)I wrote this with a friend of mine, and basically, we hope you'll enjoy!**

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A cabby stopped in front of 221B Baker Street and John stepped out. He was carrying three heavy bags full of groceries. At the door, he put them down and grabbed his keys. To his surprise, the door wasn't locked.

"_Hmmm. I guess Sherlock's already home_", he thought.

He stumbled up the stairs, trying not to fall.

"Don't worry about me, I can manage", He groaned as he dragged the bags to the kitchen.

No response.

John put the groceries in the fridge and the cupboards. Suddenly he smelled something weird. He sniffed again. It was cigarette smoke!

"Sherlock!" John shouted as he entered the living room.

"Not home", a female voice answered.

John looked surprised to the corner where the voice came from. In a chair a young woman was sitting. She looked exactly like Sherlock, but the female version. She was wearing almost the same outfit as him. The only big difference between her and Sherlock was her haircut. In opposite to his husband, this woman's hair was quite messy and a little spiked. She was leaning back, her legs crossed, smoking a cigarette. The woman stood up and flicked the cigarette out of the window. She walked towards John and pulled out her hand.

"It's nice to finally meet you, Captain Doctor John Hamish Watson-Holmes", she said with a polite smile.

John looked at her in shock and licked his lips. Once she realized he wouldn't take her offered hand, she smiled and walked towards one of the windows, while grabbing Sherlock's violin and bow.

"Err… Sorry, but, who are you?" John stammered while he stiffly walked to his armchair and dropped in it. The woman didn't seem to be a big threat. He hadn't seen any kind of weapon on her. He intently stared at the woman's back.

"You'll find out soon enough", was her only answer. She than began to play. John recognised the melody immediately. It was the first violin concert of Max Bruch. After a few minutes she suddenly stopped, much to John's disappointment. The dark-haired woman turned around, with a look on her face that John sadly had seen quite often in the last three years.

Boredom.

"When is Sherlock coming home?" she asked, while walking over to the mantelpiece, looking at all the pictures and then at the skull. A grin spread over her face. After that, she raised the violin once again and began to stroke the strings quicklywith the bow. John raised an eyebrow. Normally, when they got a client, they'd refer to his husband as 'Mr. Holmes'. But then again, he didn't know whether she was a client. In fact, he didn't know anything at all. He still answered her question though.

"He was at the Yard, about ten minutes ago, so he should be here soon." John said, "Oh and could you please not smoke in here? Sherlock is finally doing really well."

The woman shrugged and said, "I usually don't smoke anyway. I only do that when I'm under stress."

"Are you stressed then?" John asked surprised.

"No."

"Then why were you smoking?" he asked, while he got his phone out of his pocket.

"I was bored", the woman said.

"Right. Bored", John sighed. He looked on his screen. Somebody had texted him. He read the message as the woman continued to play:

_John, are you okay? SH_

John smiled and texted back:

_I'm fine, why are you asking? JW_

He wanted to put his phone in his pocket again, but there was a beep, and he chuckled. Sherlock could be so worried about him, sometimes.

_I'm asking, since there is someone in our flat, looking just like me. She's playing my violin at the moment. Are you home? 'Cause I'm coming in NOW. SH_

John heard the door open downstairs. Next, he heard very familiar footsteps walk up the stairs. He put his phone in his pocket and crossed his legs. Then the door opened and Sherlock came in.

"Oh, hello Cath", he said and then walked over to John and kissed him.

"Hello, love", he smiled.

"Hi dear", John said, "Wait, wait, what?! Cath? You know this woman?"

"Yes, indeed", Sherlock said, "This is Catherine Holmes, my little sister."

"Your sister?" John exclaimed, "Why have you never told me you have a sister?"

"It wasn't important and you didn't ask", Sherlock said calmly.

Then he walked to his sister, who, in the meantime, had put the violin down.

"Well?" Sherlock asked. He seemed to be a bit annoyed.

"So nice to see you again", Catherine said.

"Yes. Why are you here?" Sherlock asked.

"I wanted to finally meet John", Catherine said.

"Sure. And why else?" Sherlock asked calmly.

"I don't know. I guess I was bored. Let's pull a prank on someone like we used to", Catherine said. A naughty smile appeared on her face.

Sherlock smiled, thinking back to all the things they had done together.

"Sure. Why ever not?" he said. He sat down in his usual chair and smiled. Catherine smiled too and sat down on the floor.

"Why don't you grab a chair?" John asked.

"Why should I?" Catherine asked while raising an eyebrow.

"I don't know. I guess you don't have to", John muttered.

Then he said, "I know why you should have told me you have a sister, Sherlock."

"And why is that?" his husband asked with an amused smile on his face.

"Then we could have invited her to our wedding!" John said.

"Oh I was there", Catherine said calmly, "Was quite beautiful."

"Why didn't I see you then?" John asked, "And how did you even know?"

"Oh, I was sitting somewhere in the back. And Sherlock had texted me, obviously", Catherine said. Sherlock nodded and John sighed frustrated.

"Obviously." he said.

Sherlock grinned, but suddenly stiffened. He sniffed a few times and then turned to Catherine, who was grinning too.

"Did you smoke in here, Cath?" he asked while trying to perform a disappointed look. Cath just smiled.

"Just one, Sherlock. Don't be such a baby. You're doing fine and one little bit of smoke won't change that. You're not eager for one anyway. So don't make such a fuss about it."

Sherlock looked at his sister for a second and then his smile appeared again. He bowed over, looking at his sister intently.

"Where have you been the past three years?" he asked.

Catherine sighed and pinched the bridge of her nose.

"I stayed with Mycroft. I believe I might have driven him mad. He's really the most posh of the three of us, you know. But it was fun to do some of the cases that required 'legwork', as our dear brother puts it. By the way, people still don't think I'm a girl when I'm in disguise. Once, I dressed up like Mycroft and nobody noticed until Mycroft came walking in. It was brilliant." She grinned. Then a sad look entered her eyes.

"But, at one case, I got kidnapped by Moriarty. He probably thought I was you. And when he found out I wasn't, he tortured me for fun. It didn't really hurt, it was just annoying."

She rolled the sleeve of her shirt up, and both men saw long, uneven scars on her arm. There were about ten, smaller and bigger ones.

John looked at her in horror. He sat down next to her and examined her arm.

"This must've hurt really bad! And why didn't he let you go? Or kill you?"

There were numerous other questions, but Sherlock silenced his husband and let his sister continue.

"Then, one day, when they thought I was unconscious, I heard that they were going to kill me the next day. So I snuck away. Pretty easy, actually. And now I'm travelling through London. Sort of. Could you maybe use an extra pair of hands?"

Sherlock looked at John, who thought for a moment. He nodded, and Catherine smiled.

"Thanks."

Then a devious smile appeared. She clapped her hands together and placed them in front of her mouth.

"So, who are we going to prank?"

"Oh you definitely should prank the people at the Yard", John said, "That'd be hilarious."

"Really?" Catherine said a little surprised, "I didn't know you could have such ideas, John. Sherlock must have a bad influence on you."

"It's a great idea, though", Sherlock said. The same devious smile appeared on his face too. At that point, he and Catherine looked more alike than ever.

"So, any ideas then?" his little sister asked.

"Three so far, maybe four", her big brother said.

He joined his husband and sister on the floor and began to unfold his plans. At that moment, Mrs Hudson came in. She saw the three of them sitting on the floor and smiled.

"Hello there", she said, "Why don't you use chairs?"

Then she saw Catherine. She was shocked.

"Oh! Oh my! Are there two of you, Sherlock?" she stuttered.

Sherlock looked up and smiled.

"No Mrs Hudson. This is my little sister Catherine", he said.

"Your sister, Sherlock?" the elderly lady asked.

"Yes Mrs Hudson, my sister", the detective said. He was getting annoyed.

Catherine got up and walked to Mrs Hudson. She pulled out her hand and smiled.

"It's nice to meet you, Mrs Hudson", she said, "I am sorry if I startled you. It happens to everyone. Most people don't even know about my existence. That mostly works in my advantage though."

"Mrs Hudson, could Catherine stay here for the night?" Sherlock asked.

"Oh, of course", Mrs Hudson said while shaking Catherine's hand, "It's okay, dear. I just thought I was seeing double."

Catherine laughed. "It's still funny, though I have heard that over a thousand times before. And we aren't even twins."

"Really?" John asked, "How much younger are you then?"

"Two years", Sherlock said, "But in primary school this little genius skipped two years, so we were in the same class. And no one believed that we weren't twins. We also went to the same secundary and high school."

"Oh yes", Catherine smiled, "The devil twins they called us."

"I do believe we have driven most of our teachers completely mad", Sherlock said with a devilish grin on his face.

"Definitely", Catherine said with the same grin.

"I believe you on your word", John said.

"I shall return to my tea now", Mrs Hudson said, "Just came to check if you were alright."

After these words, Mrs Hudson returned to her own flat, leaving the detective, his husband and younger sister to discuss all sorts of pranks.

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**SO! Tadaaaaa! What do you think? Hope you enjoyed, and please, ****_please_****, ****_PLEASE _****review/fav/follow! Chapters will be up quicker if you do so! ;) **

**Love, Emma and Jay :D **


	2. Chapter 2 : Planning and Mycroft

**A/N: Hiya guys!  
We're back! With another chapter! **  
**Hope you'll enjoy and don't forget to review/fav/follow! They make our brains work and with working brains you'll get faster updates! ;)**

**Love, Emma and Jay**

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"So, the Yarders." Catherine said, while grabbing a pencil and a piece of paper. She drew a group of people, ignoring John's surprised look. Then she drew Anderson's office – with instructions from Sherlock - and put down the pencil, facing John. She raised an eyebrow.

"What's wrong, John?" she asked, the devious smile still present.

"Well", he looked at Sherlock for support, who simply shrugged, "Your drawing techniquesare pretty accurate."

Catherine smiled and continued with the drawing.

"Why, thank you John. Practise makes perfect, I guess. Shall we continue with the prank? Sherlock's getting a bit annoyed…"

They chuckled as Sherlock huffed and started to murmur something about husbands and little sisters and the conspiracy between those two parties. At the end, they were rolling over the floor, snickering. Finally, Sherlock sat up straight and nudged Catherine and John to do the same.

"Come on, let's continue, tomorrow they're gone for the morning, so we can put everything in place."

Catherine took a deep breath to calm herself and pulled their heads together.

"So", she said, smirking, "what's the plan?"

Sherlock kept silent for a moment and then began to explain.

"Okay. This is the plan. We are going to pull several pranks at the time, with Donovan, Anderson and Lestrade. In my bedroom I have several paint bombs, don't ask why, John, you know why. There are three. Number one will be attached to the ceiling above Anderson's desk, number two will go under his desk, and the last one will be in his chair. The first one will be triggered when Anderson sits down, so will the second one and the third. He will be covered from tip to toe with blue paint.

Next is Donovan. For this one of us will have to pickpocket her. I want her gun. We'll spray it in with glow-in-the-dark-paint. Tomorrow she has her weekly shooting training. After that she usually wipes her face off with her hands. Then the light will mysteriously go off. That will look brilliant."

"I can also break into her flat and change her usual moisturizer for a glow-in-the-dark one", Catherine said.

"You have that?" John asked.

"Of course she has that", Sherlock said, "The more unlikely it is to have something, the more likely it is that Cathy has it."

Catherine smiled naughtily.

"Okay, for the final act", Sherlock continued, "Lestrade. This will be very simple. Cath, you are going to swap places with me for the whole day and I am going to annoy Dimmock."

"So I have to pretend that Catherine is you for an entire day?" John asked with a raised eyebrow, "I'm not sure I can do that."

"Of course you can", Catherine said calmly, "When I'm in disguise, you won't even notice a difference."

"Okay, it's settled than", Sherlock said, "Cath breaks into Donovan's flat tonight and swaps the moisturizers, I will pickpocket her for her gun and I will also place the paint bombs while John distracts Anderson. After that, I will leave and then Cath will come in, pretending to be me. Got it?"

"Why do I have to distract Anderson?" John asked a little insecure.

"Because you're very good at that", his husband said, "Just improvise."

John smiled and gave his husband a quick peck on his cheek. Then he frowned.

"I need to kiss Cath, are you okay with that?"

Sherlock frowned too. Catherine looked at the two men, smiling.

"I'm okay with that, but no snogging!" Sherlock raised an eyebrow when Catherine began to laugh.

"What is it, Cath?" he asked, a bit annoyed. She sat upright again, and said, "Remember Johnny? From the seventh grade?" while she looked at her brother. A smile appeared on the consulting detective's face.

"Ahh, yes, Johnny. Your 'boyfriend'. God, I loathed that guy." When he saw John's face, he began to explain, "I replaced my sister for a day, when he had cheated on her, and went up to give him a goodbye kiss. It was hilarious. When I told him, or rather, showed him who I was, he almost stamped me into the ground, if Cathy would not have been there. She punched him, and the last thing we saw was him running away, nursing a bloody nose."

Both Holmes' snickered slightly at the memory.

"But, 'Lock", Catherine said, "I'll need to borrow your clothes. You have some old clothes for me, that you won't mind getting dirty?"

Sherlock stood up, and went upstairs, leaving his husband and his little sister for a moment.

"So", John asked while looking at Catherine, "have you got any other wounds from… Moriarty? I know your brother, and I assume you are more like him than like Mycroft, so you probably loath hospitals too. I need to check everything, okay?"

She simply nodded, shrugged her coat off, and rolled both her sleeves up.

John frowned slightly, when he also saw some deeper wounds, and began to examine them. They had healed nicely and John wondered who had looked after them. Sherlock came down again, and grinned at seeing the slight annoyance on Cathy's face.

"Enjoying your monthly check-up, Cath?" he asked teasingly.

Catherine just glared at her older brother and gave John a thankful nod when he was done. She stood up and strolled over to the window, humming the song she had played earlier on.

Suddenly, she stiffened.

"Sherlock…"

"Yes, Cath?"

"Mycroft's coming. I'm going to hide upstairs, okay?"

Sherlock growled. He began to straighten things up, while Catherine quickly but soundlessly ran up the stairs. A moment later, they heard the door open.

'Sherlock, we need to talk", Mycroft said while entering the flat.

"Whatever you wish, brother dear", Sherlock said sarcastically and sat down in his usual chair again. John grabbed a chair for Mycroft but he sat down in John's chair instead, which resulted in a slight frown from both his brother and his brother-in-law.

"Catherine has gone missing", Mycroft said, "She has been staying with me for the past three years and doing some cases for me. She has completely driven me mad sometimes, but I believe she encountered Moriarty in her last case. She has neither returned to my house nor left a message with her whereabouts. I am getting very worried. I fear the worst has happened."

"Oh", Sherlock said, not even a bit elevated, "What do you expect me to do? If Catherine is alive, I will not find her. She is far more cunning than the both of us together. And if she is dead, than we will never find her body. If it's true what you think and Moriarty has her, than she may be never found again."

"For your information, John, Catherine is our little sister", Mycroft said and then continued to his brother, "Are you sure? Is there nothing you can do?"

"My hands are tied", the detective said, "Besides, if Cathy has disappeared, that means that she doesn't want to be found."

"That's true", Mycroft sighed, "But we don't even know whether she's alive."

"Oh, we do", his little brother said, "John and I do know that."

"How?"

"She just dropped by", John said with a poker face, "She left again few moments ago. Said something about Moriarty and kidnapping."

"Really?" Mycroft asked slightly surprised.

"Yes", Sherlock said.

"Oh, well then, I also have another matter that might require your attention, brother dear", Mycroft said and handed Sherlock a case file, "Any ideas?"

"Of course", Sherlock said, "But I don't see why you would be needing my expertise on this case. Can't you do it yourself? I am kind of busy."

"Never mind your usual trivia", Mycroft said with a quite annoyed look on his face, "I'm sure that can wait."

"As a matter of fact, Mycroft, it can't", the consulting detective said, "It has to happen tomorrow and requires a lot of planning."

"Do you honestly think I care?"

"No, I don't care."

Sherlock sighed, and glanced at the case file. He then huffed in irritation.

"Mycroft", he said rather angrily, "are you seriously this incompetent? Obviously, it's the gardener. How else could there be plant seeds all over the crime-scene?"

Mycroft smiled and took the case files from his brother. He then stood up and made his leave. When the door had closed, both men heard footsteps on the stairs. A few moments later, Catherine's head popped around the corner. She grinned, and walked over to them, holding her hands behind her back. Sherlock quirked up an eyebrow.

"And, what is it my little sister has got behind her back?" he asked while the devious smile returned. Catherine said nothing but slowly revealed the item she was holding.

It was a paint bomb.

"I took the liberty to make one of these already. God, Mycroft can be such a bore."

She smirked and winked at Sherlock. The consulting detective smiled, and then pulled the doctor down for an unexpected kiss. Catherine giggled, exclaiming "Ewee! 'Lock!" playfully.

As Sherlock let John go, he smirked too.

"What… what was _that_ for!?"the doctor stammered.

Sherlock grinned.

"For being such a good liar. I like that; you should do that more often..."

"Please, 'Lock. We do have three pranks to attend. You got your clothes by the way?"

Sherlock nodded, and threw a bunch of clothes at the younger Holmes. She caught it and inspected it. She hummed in agreement while she sorted the purple shirt, the black blazer and the black tailored trousers out.

"Nice clothes. Got them from Mycroft for Christmas, didn't you?" she asked while she grabbed John's computer and began to type.

"Yes, I did. Now", he said while rubbing his hands, "let's prepare those pranks!"

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**Hope you liked it! Next chapter will be full of pranks!  
PRANK EVERYONE!-CH  
*Ahem* Cathie, not now...  
*Blush* Oh, sorry guys...  
See you!**

**Emma, Jay, Sherly, John and Cathie**


	3. Chapter 3 : The first prank

**A/N: Sorry for the long wait guys! Here's the chapter!**

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John woke up, only to find himself alone in the room. Sherlock was probably already up. He turned the alarm off and went downstairs. There, Catherine and Sherlock were discussing something over a cup of tea. He gasped, as he couldn't tell who was who. They were even wearing identical wedding rings. When Catherine noticed the doctor, she smiled.

"Good morning, John. Ready for the big day? The brake-in went as planned, as did the costume going by the look on your face."

Sherlock smirked knowingly. John chuckled.

"Now I know how Mycroft must feel all the time. Oh God, how did he survive the Christmas dinners?"

Both Holmes' grinned mischievously.

"Never mind. I don't think I really want to know", John said.

"Probably", Sherlock said with a devious smile.

"Oh my God, you even sound the same!" John exclaimed.

Catherine and Sherlock burst out laughing.

"Can you guys please stop it? It's getting kind of creepy", John said.

"I'm sorry, John. I can't. I have to practise. It has to sound absolutely perfect today", Catherine said with a smile, identical to that of her brother, on her face.

"Ah, so you're Catherine", John said, "Thanks."

Then he walked to his husband, kissed him on the lips and then grabbed a cup of coffee.

"Good morning, dear", Sherlock said, "You think you can manage an entire day without me?"

"As long as I know you're alive."

Sherlock smiled. Catherine looked a little confused.

"What did I miss on that?" she asked, "Oh wait, never mind. I remember."

"You do?" John asked.

"Yes. Though I wasn't around when Sherlock dropped from the roof, I heard it later. I saw it in the papers. You know, 'Lock, I cried."

"Really?" Sherlock asked, "I never would have thought that. Oh, well, I guess you have always been the sensitive one."

Catherine smiled and finished her tea. So did John and then they put on their coats.

"Okay, it's show time. Cath, voice check?" the detective said and his little sister answered him with the exact same voice as his own. They went downstairs and took a cab to Scotland Yard. They got a weird look from the cabby, but they ignored it. Sherlock bowed forward and began to whisper.

"Alright, let's go through it one more time. First, you two enter and go to Lestrade's office. A few minutes later, I go in, using the backdoor. I'll check on Anderson, while you go check Donovan. You'll stay at the northern part of the building and I at the southern part. At ten, we'll play the trick on Anderson. At one o'clock, it will be time for Donovan, and then, finally, the big finale, we'll get Lestrade and Dimmock together in the cafeteria at two. Got it?"

Catherine and John both nodded. The doctor wiped his hands clean once they arrived at Scotland Yard. Catherine smiled.

"Nervous, my dear husband?" she asked smugly. Despite everything, he chuckled.

"Of course, Sherlock. Shall we?" he stepped out of the cab and handed Catherine a hand. She took it, waved at Sherlock, quickly grabbed one of the two coats that were lying on the seats and pulled herself out of the cab.

"Bye, John", he heard and then the cab drove off. Catherine pulled out a hand, while she put the coat on. John took it, and sharing a devious smile, they entered the Yard.

Catherine bowed slightly backwards and whispered, "Where do we find Lestrade?" in his ear.

"On the second floor, than turn to your left and then…"

At that moment, an irritated Lestrade came out of the elevator. Catherine walked towards him, pulling John with her.

"Ah! Lestrade! There you are. I believe you wanted to speak to me?" she asked, copying her brother in every way. Lestrade looked up, surprised, but shrugged it off.

"Yes, Sherlock. I have a triple homicide for you today. Anderson and his team couldn't -"

Catherine interrupted him, huffing out of annoyance.

"Of course they couldn't track the murderer, if they could, I wouldn't be here, right?"

Lestrade just stayed silent and leaded them to his office. There, he showed them everything they needed to know about the crime-scene and the suspects.

"Alright, love, medical opinion?" she asked while she gave John a picture of one of the corpses. He looked at it for a moment.

"This man has been stabbed in the back and chest… But I can't see any details. Do you have the bodies down stairs?" he asked as he handed the picture to Lestrade. At the same moment, a ping was heard and Catherine pulled her phone out of her pocket. This was crazy; they even had the same phone! Catherine smiled and showed the text to John.

_Don't forget. In four minutes, it's ten o'clock and Anderson will be painted blue. Start heading there. SH_

He chuckled. Typical Sherlock. Lestrade raised an eyebrow.

"Anything interesting, chaps?" he asked a bit irritated.

"No, just Mycroft." Catherine said and put the phone away again. She began to walk away.

"Where are you going?" Lestrade asked, slightly stressed.

"I need the opinion of a fool. We're going to pay Anderson a visit."

"You need Anderson's opinion? Why?" John asked.

"He has been there. He should have taken pictures of everything. I want to take a look at them", Catherine said. Meanwhile John tapped her hand with either his index finger or his thumb to tell her to go left or right.

"What do you want, freak?" Anderson asked annoyed, when Catherine entered his office.

"To take a look at your pictures, Anderson. You are going to be of use to me today", the 'detective' said, while pushing Anderson towards his chair.

"Oh, alright then", Anderson said and sat down.

Catherine and John stepped back. Only a second later they heard three soft bangs shortly after each other. From everywhere around Anderson, blue paint sprayed on him. Nothing was to be seen, accept for a blue shower. Outside the window, John saw the actual Sherlock almost suffocating, trying not to burst out in laughter. When the paint shower finally stopped, Anderson wiped some paint out of his face.

"What the...?" he stammered. He didn't seem to understand what just had happened.

"What the hell?" Lestrade exclaimed as he entered the room.

"Does this happen often?" Catherine asked laughing.

"No, of course not", Lestrade said slightly irritated, "This is a police station, not a kindergarten. Sherlock, what the hell did you do?"

"Why do you think I did this?" Catherine asked snickering.

"Well, you are the one nearly dying with laughter", Lestrade said. He too couldn't hold his laughter.

"No, I'm not. John thinks it's hilarious too, don't you, love?" Catherine smiled.

John was leaning against the wall, roaring with laughter.

"I need a minute, dear", he said panting.

"Am I the only one who doesn't find this funny at all?" Anderson said whining.

"It would appear so", Lestrade snickered, "Everyone is nearly dying of laughter."

Anderson got up and shook some paint of his hands.

"I think it's best if you would go home, Anderson", Lestrade said, still laughing.

Anderson grumbled something and stiffly left the police station, muttering stuff about psychos and paint bombs. Catherine picked up Anderson's camera from his desk and went through the pictures as if nothing had happened. As if Anderson's desk wasn't half covered with blue paint. Her face was straight as usual and seemed not to show any concern about Anderson. John too managed to pull himself together, pulled one of Catherine's arms around his shoulder and took a look at the pictures too.

"Any ideas, love?" John asked.

"Of course, dear", Catherine said and gave John a small kiss, "I would say about eight, but two of them are only possible if the men have been suffocated. Would you mind and give me your opinion on this man?" she asked while winking at the window-washer who was still sniggering lightly. John took the picture from Catherine, looking at it intently.

"You're probably right. There are slight traces of bruises on the neck." he handed the picture to Lestrade, who looked at it and nodded too. Catherine smiled and began to explain the two ideas she had. John listened, but while doing so, he took her hand and began to trace the tendons with his thumb. It was something he often did with Sherlock to show their affection towards each other. Catherine got the hint and gave John that special smile that Sherlock always gave him, and he had to convince himself that it really wasn't Sherlock. When she was done, she pulled John into a hug and – ignoring Lestrade completely – gave him a peck on the lips. They looked at each other and just smiled. Catherine bowed forward and whispered softly "Best. Prank. Ever." in his ear. John chuckled.

Lestrade coughed and smirked gingerly.

"You two need to be alone for a minute?" he asked teasingly.

John ignored him, but Sher- Catherine stepped away slightly and began to ask Lestrade questions about all kind of things that seemed irrelevant about the crime-scene.

Suddenly, she gasped and clapped her hands together dramatically like her brother.

"Of course! The third victim! That one hasn't been suffocated, right? He's been killed by a bullet! He's the murderer, he didn't want to be caught because then he would have to put up with his wife or another close relative, but he couldn't suffocate himself, so he killed himself with the same gun which he used to threaten his other two victims with!"

Lestrade looked at the 'detective' and swallowed.

"And you got all of this from a picture?" he asked while he looked at her with big eyes.

She smirked and placed an arm around John's waist.

"Hey, I am the only consulting detective in the world. And besides that, it wasn't _that_ hard!"

She then looked at her watch. _Eleven o'clock_. She seized John's wrist and began to drag him out of the room when Lestrade stopped them.

"Ho, wait a minute, guys! You're going to help to clean this mess up."

He raised a hand to stop Catherine from speaking and crossed his arms.

"Don't try to tell me you weren't behind that! Only you could do that unnoticed, now go get some cleaning equipment and go help the janitors."

Catherine grimaced but complied and they went down to the basement. Once they were there, she grinned and turned around, facing a dark corner in the room.

"Hi, 'Lock!" she said smiling. Out of the shadows stepped a smiling man in a window washer-suit. John chuckled and went to give his husband a hug.

"Jesus, Sherlock. That was brilliant! How did you manage to get passed the Yarders?" John asked. The real detective smiled and pointed towards his younger sister.

"Well, I must say, Cathy did a great job indeed."

Catherine laughed at the surprised look on John's face. Then she turned serious again.

"I do need to clean it up. But we'll have the time till one o'clock anyway, but I'd rather spent that time solving cases, but oh well…"

She grabbed some buckets, cloths and soap. She gave one to John and then filled a third one with water.

"Let's go!" she smiled and walked back to the elevator as John gave Sherlock another quick peck, and then followed Catherine.

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**So? Whaddya think? Anyways, please spread the word! And thanks to every hit, review, favourite and follow! :D**


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